The present invention relates to an apparatus and a method for recording video information, an apparatus and a method for reproducing video information, a recording medium, and a program, and particularly to an apparatus and a method for recording video information, an apparatus and a method for reproducing video information, a recording medium, and a program that can properly manage security information of an AV signal recorded on a recording medium.
Recently, various optical disks have been proposed as disk type information recording media detachable from recording and reproducing apparatus. Such recordable optical disks have been proposed as several-gigabyte large-capacity media, and are greatly expected as media for recording digital video (moving picture) signals.
One of the encoding methods for digitally compressing digital video information is an MPEG (Motion Picture Experts Group) 2 method. MPEG2 is also applied to the case where digital video information is recorded on a recording medium. When analog video information is to be recorded on a recording medium, for example, the video information is encoded into an MPEG2 form, and then an encoded bit stream is recorded on the medium. Also, in the case of the recently launched digital television broadcasting, a video program encoded by the MPEG2 method is transmitted in a format referred to as a transport stream. When a digital broadcast is to be recorded on a recording medium, a method is used which records the transport stream as a digital signal without decoding or re-encoding the transport stream.
When video information is recorded on a recording medium in a digital signal format, the video information can be copied onto other recording media without any degradation. However, this presents a serious problem to copyrighters of the video contents. Accordingly, in order to restrict the copying of video information, a method is used which provides video information with CCI (Copy Control Information) indicating copy generation management information of “Copy Free (copy permitted),” “Copy Once (copy permitted only for one generation),” “No More Copy (copy not permitted for generations subsequent to the present generation),” and “Copy Prohibited (copy not permitted).” For example, there is a CGMS (Copy Generation Management System) signal, and a CGMS signal for an analog interface is referred to as CGMS-A and a CGMS signal for a digital interface is referred to as CGMS-D. The analog CGMS-A is also referred to as VBID because an ID is superimposed in a VBI (Vertical Blanking Interval) of the video information. This is standardized as EIAJ CP-1204.
There is a method of encoding a descriptor having CCI in order to transmit the information in a transport stream. Descriptors of this type include a DTCP descriptor defined by DTLA (Digital Transmission Licensing Administrator) and a digital_copy_control_descriptor defined by ARIB and used in Japanese BS digital broadcasting. For more severe copy restriction, a method has recently been considered which embeds copy generation management information referred to as a watermark in baseband video information or an MPEG video stream. Standardization of watermarks is currently under way, and a Millennium format and a Galaxy format have been proposed.
When video information is recorded on a recording medium, recording restriction is required to be imposed properly according to the CCI of the input signal. In general, a user can record video information on a recording medium only when the CCI of the input signal indicates either “Copy Free (free copying permitted)” or “Copy Once (copy permitted only for one generation).” When the CCI of the input signal indicates “Copy Once (copy permitted only for one generation),” the CCI of the video information on the recording medium needs to be updated to “No More Copy (copy not permitted for generations subsequent to the present generation).”
For easy grasping of contents of video information recorded on a recording medium, a still picture representative of the contents and a picture obtained by extracting as a still picture a particular scene from the contents may be recorded separately from the video information. These still pictures are referred to as thumbnail pictures. By displaying a list of such thumbnail pictures on a menu screen for a user to select a reproduction start point of the video information recorded on the recording medium, it is possible to provide a user-friendly interface. A thumbnail picture may be a picture selected from the recorded video information, or may be a picture captured from a personal computer, a digital still camera or the like into the recording medium.
As described in the related art, considerable attention is paid to the management of contents protection information when video information is recorded on a recording medium. On the other hand, no attention is paid to the management of contents protection information when a thumbnail picture is recorded. This is expected to present a problem in the future. More specifically, when recording in the digital video information format becomes dominant in the future, proper management of contents protection information is also expected to be required when a thumbnail picture is recorded. For example, a picture of a popular character in a movie or a television program is often copyrighted, and therefore illegal copying of the picture presents a problem to the copyrighter.
When a picture selected from input video information with CCI indicating “Copy Once” is recorded as a thumbnail picture on a recording medium, the thumbnail picture should be managed with “No More Copy” as with the contents. Also the thumbnail picture should be encrypted and then recorded. Thereby, even if a malicious person illegally copies the thumbnail picture onto another recording medium as identical data on a bit-by-bit basis, it is possible to prevent reproduction of the illegally copied thumbnail picture.
Thus, when video information with CCI indicating “Copy Once” is to be recorded, the video recorder should be provided with the function of encrypting and recording the video information and thumbnail pictures thereof. The encrypting method may use DES, Triple-DES, or AES, for example.
On the other hand, there may be a video recorder as a product for recording only video information with CCI indicating “Copy Free.” For example, current terrestrial analog TV broadcasting can be handled as contents with CCI indicating “Copy Free” when used only by a general user himself/herself, and thus there may be a video recorder for recording only terrestrial analog TV broadcasts. In this case, the video recorder does not need to have a function of encrypting video information and thumbnail pictures thereof for recording (of course, the video recorder may encrypt and record video information and thumbnail pictures thereof).
When an application of recording video information and thumbnail pictures thereof is considered, in a case of a removable recording medium for a video recorder, encrypted thumbnail pictures and non-encrypted thumbnail pictures may be mixed with each other on the recording medium. In this case, when there is no system provided for distinguishably managing the encrypted thumbnail pictures and the non-encrypted thumbnail pictures, there occurs a problem of not knowing which pictures are the encrypted thumbnail pictures and which pictures are the non-encrypted thumbnail pictures on the recording medium.